Research dealing with the cytomegaloviruses will emphasize the isolation and physical characterization of early (not dependent on DNA synthesis) and neutralizing antigens. Once isolated, the antigens will be tested in assays of humoral and cellular immunity to establish criteria of protective immunity in individuals who are symptomatically or asymptomatically infected. Additionally, antisera will be prepared to the isolated neutralizing antigens and used in further studies of the antigenic heterogeneity of the human cytomegaloviruses. Efforts will continue to produce high titers of varicella-zoster virus. Primary and continuous cell cultures from various sources will be tested for their ability to produce cell-free virus. Physical techniques will be employed to concentrate the virus. If virus stocks of sufficiently high titer are obtained, attempts will be made to establish an animal model for the study of viral latency and reactivation.